Disclaimer, I havent fully investigated the problem, I only noticed this when I was working on the locking hubs the other day.

I have an 86 deluxe 4x4 auto pickup. The previous owner used it as a woods truck/hunting buggy. For me it's an offroad toy as well so not my dd. The po told me they disconnected the drum brakes at the master cylinder because they kept getting gummed with sand. I believe it. It is disconnected at the master, but while I was working on it the other day I noticed this. I'm assuming this is the return line for the lspv for the rear brakes?

Right behind the passenger wheel

 

Thats what it is. I would recommend getting the rear brakes working again. Not only does it make the truck not stop as good, if you ever loose the front brake circuit from a leak or whatever, your truck isn't coming to stop.

 

That's the plan. I'm working front to back with the trucks issues. Did a refresh on the locking hubs, valve cover gaskets, fluid flushes, I have to drop the gas tank to check the sending unit so I'll take a look at the brake lines while I'm there. I'll be rebuilding the drums for now until I can do a disc brake swap. I was just curious what that line could be and why it would be blocked off. Thanks for the help!